Balloon angioplasty has been shown to be superior to medical treatment for the relief of symptoms and ischemia in patients with single vessel coronary artery disease. Unfortunately, the outcome of PTCA in women has not been as favorable as the outcome in men. Women tend to be older than men at the time of angioplasty and are less likely than men to remain symptom free during serial follow-up. Furthermore, the long-term outcome of PTCA is compromised in all patients by restenosis which occurs in 30- 50% of patients within 3-6 months of the initial procedure. Since angioplasty is performed on over 120,000 women each year in the United States, restenosis in 30-50% of these patients represents a significant public health problem for older women. A variety of metallic intra- coronary stents have been employed in an attempt to improve PTCA success rates. These devices have been shown to enhance post-PTCA lesion geometry and to improve long-term outcome in comparison to PTCA. Nevertheless restenosis still occurs in 22% and 32% of stented patients. Thus, in spite of significant advances in technique and adjunctive medical treatment, restenosis after percutaneous coronary revascularization remains a major problem. Moreover, women have fared comparatively poorly after PTCA with less long-term relief of symptoms and a trend towards reduced survival compared to men. Interestingly, two recent retrospective studies have suggested that women who took estrogen replacement after their angioplasty had less restenosis and better long- term outcome than their non-estrogen taking counterparts. Accordingly, the primary goal of this Proposal is to investigate the potential of estrogen replacement therapy to inhibit restenosis after angioplasty and stenting in older women. Coronary heart disease is the leading cause of depth among post-menopausal women. This is in stark contrast to the relative freedom from coronary disease which is enjoyed by most pre- menopausal women. Elucidation of the effect of estrogen on the arterial response to coronary stenting will provide important insights into the mechanisms of the atherosclerotic disease process itself, as well as providing the opportunity to understand how best to extend the protection enjoyed by pre-menopausal women into women in older age groups, as well as into the male population.